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# AWS::OpenSearchServerless::Index Method
<a name="aws-properties-opensearchserverless-index-method"></a>

Configuration for k-NN search method.

## Syntax
<a name="aws-properties-opensearchserverless-index-method-syntax"></a>

To declare this entity in your CloudFormation template, use the following syntax:

### JSON
<a name="aws-properties-opensearchserverless-index-method-syntax.json"></a>

```
{
  "[Engine](#cfn-opensearchserverless-index-method-engine)" : String,
  "[Name](#cfn-opensearchserverless-index-method-name)" : String,
  "[Parameters](#cfn-opensearchserverless-index-method-parameters)" : Parameters,
  "[SpaceType](#cfn-opensearchserverless-index-method-spacetype)" : String
}
```

### YAML
<a name="aws-properties-opensearchserverless-index-method-syntax.yaml"></a>

```
  [Engine](#cfn-opensearchserverless-index-method-engine): String
  [Name](#cfn-opensearchserverless-index-method-name): String
  [Parameters](#cfn-opensearchserverless-index-method-parameters): 
    Parameters
  [SpaceType](#cfn-opensearchserverless-index-method-spacetype): String
```

## Properties
<a name="aws-properties-opensearchserverless-index-method-properties"></a>

`Engine`  <a name="cfn-opensearchserverless-index-method-engine"></a>
The k-NN search engine to use  
*Required*: No  
*Type*: String  
*Allowed values*: `nmslib | faiss | lucene`  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`Name`  <a name="cfn-opensearchserverless-index-method-name"></a>
The algorithm name for k-NN search.  
*Required*: Yes  
*Type*: String  
*Allowed values*: `hnsw | ivf`  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`Parameters`  <a name="cfn-opensearchserverless-index-method-parameters"></a>
Additional parameters for the k-NN algorithm.  
*Required*: No  
*Type*: [Parameters](aws-properties-opensearchserverless-index-parameters.md)  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)

`SpaceType`  <a name="cfn-opensearchserverless-index-method-spacetype"></a>
The distance function used for k-NN search.  
*Required*: No  
*Type*: String  
*Allowed values*: `l2 | l1 | linf | cosinesimil | innerproduct | hamming`  
*Update requires*: [No interruption](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/using-cfn-updating-stacks-update-behaviors.html#update-no-interrupt)